1. Field of the Invention
The invention relates to an analog to digital converter (ADC), and more particularly to an ADC that uses successive approximation techniques.
2. Description of the Related Art
Analog to digital converters (ADCs) are widely used in a variety of applications, such as medical systems, audio systems, test and measurement equipment, communication systems, and image and video systems, etc. The most common ADC construction comprises flash ADCs, pipeline ADCs and successive approximation register (SAR) ADCs. The power consumption of the SAR ADC is smaller than the flash ADC and the pipeline ADC. Thus the systems with limited power supply, such as portable devices, usually use SAR ADCs.
The conversion accuracy of the SAR ADCs is mainly subject to the DAC mismatch and offset errors. Particularly, for the switched-capacitor SAR ADCs, the capacitor mismatch is the dominant one.